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第三节设计因素机械构件由于设计不合理或考虑不周,而造成的失效实例是很多的,其原因在机械构件设计中常有许多难以计算的因素存在。例如机械构件经常是处于复杂的受力状态之下,无法精确而全面地计算出作用在构件上的所有载荷;另外,即使计算出的应力与实际应力也不能精确地符合。在这里仅就失效分析中常遇到的几个问题简介如下: 1 许用应力的选择机械构件的种类虽然很多,但是设计时所应考虑的基本要求却往往是相同的。即保证构件有足够的强度及一定的使用寿命,必须规定它能承受的最大应力,通常称之为许用应力[σ]。
Section III Design Factors Mechanical components due to poor design or ill-considered, and the failure caused by a lot of examples, the reason for the mechanical components often have many difficult to calculate the existence of factors. For example, mechanical components are often subjected to complex stress conditions and can not accurately and comprehensively calculate all the loads acting on the component. In addition, even calculated and actual stresses do not exactly match. Here are just a few of the problems often encountered in failure analysis are as follows: 1 The choice of allowable stress Although there are many types of mechanical components, the basic requirements for design should always be the same. That is, to ensure that the component has sufficient strength and a certain service life, it must stipulate the maximum stress that it can withstand, commonly referred to as allowable stress [σ].